The Bluetooth® technology draws attention as short-range radio communication means, and a variety of apparatuses featuring the Bluetooth interface have been developed and commercially available.
Radio communication systems such as the Bluetooth using radio waves have advantages such as no directivity and high transmission efficiency over infrared communication systems. When a communication, such as an IrDA, having a high directivity is used, apparatuses in communication must face each other in alignment. The communication system such as Bluetooth apparatuses is free from such restrictions.
The Bluetooth specifications are controlled by Bluetooth SIG Inc., and the detailed information about the Bluetooth specifications is available from Bluetooth SIG Inc. In a communication in compliance with the Bluetooth specifications, an apparatus called a master broadcasts a device detecting message to apparatuses present in a surrounding area to detect the apparatuses.
The master detects apparatuses present in the surrounding area, namely, communicable apparatuses, by reply messages transmitted from an apparatus (a slave) that has received the device detecting message.
When establishing a communication with a particular apparatus from among detected apparatuses, the master identifies each apparatus based on identification information contained in the reply messages, and then establishes the communication with that particular apparatus.
In the Bluetooth communication, information called a Bluetooth address identifying each apparatus is assigned the apparatus. The Bluetooth address, unique (particular) to each apparatus, is used in various processes such as a management of apparatuses.
A Bluetooth system typically employs a piconet, i.e., a network containing a master and slaves, and in the same piconet, a maximum of seven slaves belong to a single master. All apparatuses belonging to the same piconet are synchronized in a frequency axis (a frequency hopping pattern) and in a time axis (a time slot).
A plurality of piconets may be linked to form a network, which is called a scatternet.
The Bluetooth specifications specify data exchanged over the radio communication, and a profile formulated for each of services, and the service provided by each apparatus is described using the profile.
For example, a PAN (Personal Area Network) profile currently being formulated as one of the profiles specifies a communication method between slaves. The apparatuses belonging to the piconet organized based on the PAN profile exchange a variety of data over the piconet as a network. Similarly, a planned standard is expected to define the scatternet as a single network where a variety of data is exchanged over. The network may be the one based on an IP (Internet Protocol).
When a network is organized, which apparatus to serve as a master, which apparatuses to serve as slaves, and what service to be used in communication must be determined. The master acquires information about apparatuses in the surrounding area using the device detecting message, and determines these network parameters in response to an instruction from the user.
In a Bluetooth radio communication system, the device detecting message is broadcasted to all apparatuses within a search area (within a radium of 10 meters to 100 meters). The user recognizes information presented on a display, and selects an apparatus to communicate with from among apparatuses that have transmitted reply messages in response to the device detecting message. This is a time-consuming operation.
More specifically, since the user must select an apparatus each time communication is made, the communication system is not user friendly. As the Bluetooth compatible apparatuses are widely used, the ease of use of the system is more adversely affected.
The user needs to select a desired service from among services reported by the apparatuses when data is actually exchanged. This step consumes more time before starting communication.
Even after the selection of the apparatus to communicate with and the selection of the service with the selected apparatus, the user is further forced to enter a numeric input of a predetermined digit called a pass key to both apparatuses for communication. The input of the pass key is particularly required to establish a first communication with an apparatus which requires security. The pass key input degrades the ease of use of the system.
The above-referenced steps presents difficulty for user to organize a communication group (a network) through a Bluetooth communication formed of a plurality of apparatuses.